On Thu, 28 Apr 2005, Amos wrote:
Maybe *ideally* it needs to be fixed by the MTA. However, just casually following this list and the postfix-users list, whenever the issue of NUL characters have come up, it has always been centered around Cyrus. I know that there are folks using Postfix with other IMAP servers, and never once have I noticed this topic in relation to these systems. As best as I can recall, it has always been in relation to Cyrus.
So, my take on this is that while it may be *ideally* better dealt with by the MTA, perhaps *practically* it is more productive to remedy the software that is bitching the most about it. It certainly would cut down on the frequency that this issue comes up on this list....
Maybe I need to read back in this thread to remember, but what was the suggested solution in Cyrus?
I think Cyrus is correct to bounce these messages back to the sender. Accepting them seems somewhat dangerous. What happens when parts of Cyrus or the IMAP protocol see a NUL? Can we be sure that a NUL character won't cause problems "downstream"?
A cursory look through rfc3501 shows:
4.3.1. 8-bit and Binary Strings
8-bit textual and binary mail is supported through the use of a [MIME-IMB] content transfer encoding. IMAP4rev1 implementations MAY transmit 8-bit or multi-octet characters in literals, but SHOULD do so only when the [CHARSET] is identified.
Although a BINARY body encoding is defined, unencoded binary strings are not permitted. A "binary string" is any string with NUL characters. Implementations MUST encode binary data into a textual form, such as BASE64, before transmitting the data. A string with an excessive amount of CTL characters MAY also be considered to be binary.
9. Formal Syntax
...
(3) The ASCII NUL character, %x00, MUST NOT be used at any
time.It seems pretty clear that even if you accepted messages with NUL characters, you'd have to transform/strip that NUL anyways.
Food for thought.
Andy --- Cyrus Home Page: http://asg.web.cmu.edu/cyrus Cyrus Wiki/FAQ: http://cyruswiki.andrew.cmu.edu List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html
